1. Field of the Invention
The present invention relates to an adhesive sheet for dicing glass substrate and a method of dicing glass substrate. This invention also relates to a cut piece of glass substrate, which is obtained by this method. The adhesive sheet for dicing glass substrate can be utilized in various industrial fields and is particularly useful as e.g. a glass substrate-fixing sheet used for sticking and fixing a glass substrate provided with semiconductor circuits or a glass substrate used in optical communication etc. in order to cut the glass substrate into small pieces.
2. Description of the Related Art
Semiconductor products or optical articles made of glass, quartz, rock crystal, sapphire or lens are produced by cutting and separating (dicing) a glass substrate having formed various circuits or subjected to surface treatment etc., to form small pieces serving as individual elements or parts. In this production process, the glass substrate having an adhesive sheet stuck thereon is subjected to a dicing step, a washing step, a drying step and a pick-up step respectively and then to a subsequent step. The adhesive sheet used in the dicing to pick-up steps of the glass substrate is desired to exhibit sufficient adhesion to cut pieces in the dicing to drying steps and to exhibit adhesion in the pick-up step to such an extent that its adhesive does not adhere to the cut pieces.
As the adhesive sheet for dicing glass substrate, a dicing adhesive sheet applied to semiconductor wafers has been used. The thickness of such a dicing adhesive sheet is usually about 70 to 120 μm.
The glass substrate is thicker than a semiconductor wafer and is thus diced by using a blade having a thickness of about 150 to 300 μm in order to conduct stable dicing. Due to a round top of the dicing blade, however, a cut piece from a conventional dicing adhesive sheet has a broader width in a lower section, to have an irregular shape like skirt.
Further, the glass substrate is very brittle and easily broken. Accordingly, when the adhesive sheet for fixing the glass substrate is significantly deformed by pressure from the dicing blade, the glass substrate cannot endure the deformation and is thus broken to cause chipping or to scatter chips, causing a problem in qualities of cut pieces.
An object of the present invention is to provide an adhesive sheet for dicing glass substrate, which can give cut pieces excellent in shape and hardly causes cut pieces to be chipped or to scatter chips. Another object of this invention is to provide a method of dicing glass substrate by using this adhesive sheet. A still other object of this invention is to provide a cut piece of glass substrate, which is obtained by this method.